<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>选择器</title>
    <script src="../js/jquery-3.3.1.min.js"></script>
</head>
<body>
            <div id="div">我是div1</div>
            <div class="cls">我是div2</div>
            <div class="cls">我是div3</div>

</body>

<script>
    onload =function () {
        let div = $("#div");
        alert(div.html())
    }
        let array=$(".cls");
        for (let i = 0; i <array.length ; i++) {
            alert(array[i].innerHTML)
        }

</script>

</html>